Method for isolating a sample well of a test card for analysis, and resulting test card

ABSTRACT

The invention relates to a method for isolating at least one fluid sample well laid out in a test card for analysis, said test card including a plate ( 3 ) having at least one first main face from which is laid out at least one channel communicating with at least said well, this first face being coated with a membrane ( 17 ) provided with an adhesive ( 18 ) and which will cover said channel with a covering area ( 17   1 ), the method for isolation including a phase for introducing a fluid sample into at least said well and a phase for isolating said well consisting of exerting a force on at least one portion of the covering area ( 17   1 ) of the adhesive membrane ( 17 ) for ensuring displacement of the adhesive into an obturation area for the sample well.

The present invention relates to the general technical field of devicesand machines for testing biological samples, and more particularly testcards for analysis in which channels are laid out for supplying fluid asfar as wells suitable for receiving a reagent and a fluid or test samplecontaining a microbiological agent such as a microorganism.

The object of the invention more specifically aims at a technique givingthe possibility of ensuring obturation of these wells in order to avoidany risk of contamination between these different wells.

In the state of the art, many publications describe various test cardsfor analysis which have a well or a reaction enclosure designed forreceiving a reagent and a fluid sample containing a microbiologicalagent such as a microorganism. Such a test card which is for exampledescribed by patent EP 0 908 728, includes a plate in which are laid outwells communicating with an admission port, via a network of supplychannels laid out on either one or on both of the main faces of theplate.

Conventionally, in each of the wells, a reagent is deposited during themanufacturing of the test card. The reagent usually contains a culturemedium for a microbiological agent contained in a fluid or test sample.Deposition of a different reagent in each of the wells of the card isthus known for carrying out identification tests on a fluid samplecontaining a microbiological agent or an unknown organism. The use ofthe cards for testing the sensitivity of the microbiological agent toantibiotics is also known by depositing various antibiotic reagents inthe wells.

In the state of the art, application of a transparent adhesive membraneon either one or on both of the surfaces of the plate is known in orderto cover the wells and the fluid supply channels. This transparentadhesive membrane prevents the reagent from being cleared from the wellduring transport and handling and is also used as a liquid barrier forpreventing leakage over the edges of the well of the fluid sampleintroduced into the well.

It should be considered that there exists a real possibility of fluidiccommunication between the sample wells during the various steps forprocessing the test card, which may cause cross-contamination betweenthe various wells. Such a risk is all the more significant since thedistance between the wells tends to decrease due to the requirements oflaying out a larger number of wells on a test card, the dimensions ofwhich remain identical.

In order to reduce the risk of cross-contamination, the prior artproposed various solutions. For example, U.S. Pat. No. 6,128,899proposes the filling of the various supply channels via an additionalfluid in order to separate the wells from each other. Patent applicationUS 2008/0112855 proposes isolation of the wells from each other byinterposing a heat-sensitive obturator allowing the opening or theclosing of the supply channels.

It emerges that these techniques for avoiding contamination between thesample wells require modification of the method for manufacturing thetest cards by integrating obturation means on the card. These techniquesprove to be difficult to apply in practice.

Patent application US 2004/0157343 proposes the closing of the samplewells by locally deforming the test card at right angles to the supplychannel. The deformation of the test card is ensured via a heated punch.In practice, this technique is delicate to accomplish insofar that itseems to be difficult to control the temperature and the deformation ofthe test card. The consequence is a significant risk of degrading thesample wells, which may compromise the integrity of the test process forthe microbiological samples.

In the same sense, patent application WO 2004/011149 describes a methodand a device for making obturators in a circuit laid out on a substrate.The circuit includes first and second cavities connected togetherthrough a channel made in an elastically deformable material. Thesubstrate is covered with an elastically deformable membrane andcovering at least the channel in order to delimit communication betweenthe first and second cavities when the membrane is in a non-deformedcondition. The method provides deformation both of the membrane and ofthe material making up the channel by means of specific tools, in orderto produce an obturator. According to an alternative embodiment,provision is made for deforming the membrane in order to bring theadhesive layer into contact with the channel in order to ensureobturation between the first and second cavities.

This technique teaches the use of a deformable substrate and of anelastically deformable adhesive membrane, which has a significant riskof degrading the sample wells. Moreover this technique does notundoubtedly ensure isolation of the sample wells.

The present invention therefore aims at finding a remedy to thedrawbacks of the state of the art by proposing a novel method forisolating the sample wells of a test card for analyses, this novelmethod being efficient and simple to apply, while giving the possibilityof keeping conventional techniques for manufacturing test cards foranalyses.

In order to attain such a goal, the object of the invention relates to amethod for isolating at least one fluid sample well made in a test cardfor analyses, said test card including a plate having at least one firstmain face from which at least one channel communicating with at leastsaid well is laid out, this first face being covered with a membraneprovided with an adhesive and which will cover said channel with acovering area, the method for isolation including:

-   -   a phase for introducing a fluid sample in at least said well,    -   a phase for isolating said well, according to an isolation area,        consisting of exerting a force on at least one portion of the        covering area of the adhesive membrane in order to displace it        as far as having it fit the shape of the wall of the channel so        as to allow adhesion of said covering area of the adhesive        membrane onto the wall of the channel. According to the        invention, the method consists of exerting a force on the        covering area of the adhesive membrane in order to ensure        displacement of the adhesive in an obturation area for the        sample well contiguous to the isolation area.

The method according to the invention includes as a combination eitherone or both of the following features:

-   -   exerting the force on the covering area of the adhesive membrane        located overhanging at least one channel for ensuring the        displacement of a volume of adhesive, greater than the volume of        the obturation area of the channel,    -   exerting the force on the covering area of the adhesive membrane        located overhanging at least one distribution channel, in order        to ensure the displacement of the adhesive in at least one        obturation area located in a filling channel communicating        between a sample well and the distribution channel,    -   exerting the force on the covering area of the adhesive membrane        during a relative displacement between the test card and the        pressing member along a direction parallel to the direction of        extension of at least one distribution channel in order to        ensure the displacement of the adhesive in a filling channel        communicating with said distribution channel,    -   exerting a force on the covering area of the adhesive membrane        by means of a pressing member having a supporting end with a        section mating the section of the channel,    -   exerting a force on the covering area of the adhesive membrane        according to a pressure comprised between 0.3 and 0.7 kg/cm² and        preferably of the order of 0.6 kg/cm²,    -   displacing the test card along a direction corresponding to the        translational movement of a system for displacing the test card,        belonging to a test card processing machine.

Another object of the invention is to propose a novel test card foranalyses, with a simple design and providing complete isolation betweenthe sample wells while retaining the integrity of the sample wells.

In order to attain such a goal, the object of the invention relates to aplate having at least one main face from which is laid out at least onechannel communicating with at least one sample well, this first facebeing coated with an adhesive membrane in order to cover said channelwith a covering area, at least one portion of the covering area of theadhesive membrane at least locally fits the shape of the wall of thechannel, in an isolation area. According to the invention, the test cardincludes at least one area for obturating the sample wall, adjacent tothe isolation area and filled with the adhesive of the adhesive membranefrom the obturation area.

Advantageously, the test card according to the invention includes as acombination, either one or both of the following additional features:

-   -   at least one obturation area located in a distribution channel,        at least at the intersection with at least one channel for        filling a sample well, the isolation area adjacent to the        obturation area being located in the filling channel,    -   the adhesive membrane is coated with an adhesive having a        thickness comprised between 15 and 100 μm,    -   the distribution or filling channel has a section comprised        between a semi-circle of height R and with a width equal to 2R        on the one hand, and a circular portion with a width √5.R/3 and        a height equal to R/3, on the other hand.

Another object of the invention is to propose an obturation device forapplying the method according to the invention.

According to this aspect of the invention, the obturation device forapplying the method for isolating at least one sample well laid out in atest card for analysis includes a system for exerting a force on atleast one portion of the covering area of the adhesive membrane in orderto displace it as far as causing it to at least locally fit the shape ofthe wall of the channel in order to isolate said well with respect tothe channel by driving out the adhesive by applying the force on theadhesive membrane.

Advantageously, the obturation device includes either one or both of thefollowing additional features:

-   -   the system for exerting a force includes a pressing member with        a section mating the section of the channel,    -   the pressing member has a rounded supporting end.

According to a first alternative embodiment, the pressing member isdriven for moving closer to/moving away from the test card so as toallow application of at least one portion of the covering area of theadhesive membrane onto the wall of the channel.

According to a second alternative embodiment, the pressing member ismounted so as to be mobile in rotation for rolling on at least oneportion of the length of the channel.

Advantageously, another object of the invention is to propose aprocessing machine including an obturation device according to theinvention.

According to a preferred alternative embodiment, the obturation deviceis mounted so as to act on the test card during a translational movementof conveying means belonging to the processing machine.

Various other features emerge from the description made below withreference to the appended drawings which show, as non-limiting examples,embodiments of the object of the invention.

FIGS. 1 and 2 are respectively planar views of the front and rear facesof an exemplary embodiment of a test card applying the method accordingto the invention.

FIGS. 3 to 5 are large scale cross-sectional views of a test cardshowing three characteristic steps of the method according to theinvention, i.e. before applying any force on the adhesive membrane, whenapplying a force on the adhesive membrane and after suppressingapplication of a force on the adhesive membrane of the test card,respectively.

FIG. 6 is a schematic view of an exemplary application of the methodaccording to the invention aiming at applying a force on the adhesivemembrane of the test card along a direction perpendicular to the face ofthe test card.

FIG. 7 is a schematic view of another exemplary application of themethod according to the invention aiming at applying a force on theadhesive membrane of the test card, simultaneously with displacement ofthe application of the force along the extension direction of thechannel.

FIGS. 1 and 2 illustrate an exemplary embodiment of a test card 1including sample wells 2, isolated from each other. Before describingthe obturation characteristics of the wells 2, it is recalled that atest card 1 for analysis generally appears as a plate or support 3 witha small thickness having a first so-called main front face 4 and asecond so-called rear main opposite face 5. In the illustrated example,the plate 3 has a rectangular shape and has two longitudinal edges 3 ₁parallel with each other and connected through two transverse edges 3 ₂also parallel with each other.

This test card 1 includes at least one, and in the illustrated example,a plurality of wells 2 laid out in rows and columns in a preferredembodiment. In the illustrated example, the wells 2 distributed intoeight rows and eight columns open out on both faces 4 and 5. Of course,the number, the geometry and the arrangement of the wells 2 may beachieved in a different way. Conventionally, the wells 2 are pre-filledwith reagents and/or culture media in order to be able to conduct abiological test on samples.

The test card 1 also includes at least one and generally one network ofchannels 9 a, 9 b, 9 c laid out in the plate 3 for conveying the fluidsample from a fluid admission port 11 as far as the wells 2. The supplyor conveying channels 9 a, 9 b, 9 c are laid out on either one or bothof the main faces 4, 5. These supply channels may be distributed indistribution channels 9 a connected to the admission port 11 and onwhich, filling channels 9 c are connected in parallel, each ending upwith a well 2.

In the illustrated example, the test card 1 includes fluid distributionchannels 9 a laid out on the surfaces of the front 4 and rear 5 faces ofthe plate 3. Advantageously, the portion of the distribution channels 9a to which the filling channels 9 c are connected, extend along adirection parallel to the longitudinal edges 3 ₁. The distributionchannels 9 a communicate with each other from one face to the other, bymeans of connecting channels 9 b crossing right through the plate 3.These distribution channels 9 a communicate with the admission port 11via an admission manifold 12.

These distribution channels 9 a are connected to the wells 2 via fillingchannels 9 c laid out on both faces 4, 5 of the plate. Each well 2 thuscommunicates with a distribution channel 9 a via one filling channel 9 claid out on one face of the plate or with two filling channels 9 c madeon both faces 4, 5 and communicating in series by means of a connectingchannel 9 b crossing right through the plate 3.

According to an alternative, the wells 2 are in communication withbubble traps 13 via passages 14 which allow all the bubbles which may beformed in the well 2 to be directed as far as the corresponding bubbletrap 13.

An adhesive membrane 17 is applied on each face 3, 4 of the plate. Theadhesive membrane 17 is preferably transparent and includes a supportfor an adhesive 18. This support which has a thickness comprised between18 and 100 μm, is for example made with a PMP (polymethyl-pentene) filmhaving a thickness of the order of 50 μm or with a BOPP (biaxialoriented polypropylene) film with a thickness of the order of 19 μm.This adhesive membrane 17 is conventionally coated with an adhesive 18having a thickness of the order of 30 μm and preferably comprisedbetween 15 and 100 μm.

This adhesive membrane 17 has an elastic or plastic deformabity. Thisadhesive membrane 17 has an elongation at break greater than or equal to160%.

The adhesive membrane 17 thus covers the wells 2 and the channels 9 a, 9b, 9 c in order to ensure their closing in the plane of the faces 3, 4of the card. It should be noted that upon applying the adhesive membrane17 onto the plate 3, the adhesive membrane 17 adheres to the faces 4, 5without adhering to the walls 9 ₁ of the channels 9 a, 9 b, 9 c laid outas recesses from the faces 4, 5 of the plate 3. Thus, the adhesivemembrane 17 in particular covers the distribution channels 9 a and thefilling channels 9 c, through a so-called covering area 17 ₁. In otherwords, this covering area 17 ₁ corresponds to the portion of theadhesive membrane 17 located facing, overhanging or opposite thedistribution channels 9 a and the filling channels 9 c.

This phase for manufacturing such a test card 1 is not described morespecifically insofar that it does not specifically belong to the objectof the invention and is well known to one skilled in the art. Themanufacturing of such a test card 1 is for example described in moredetail in U.S. Pat. No. 5,609,928, EP 0 785 433 or EP 0 745 856. Ofcourse, the object of the invention is applied to a test card 1different from the one described as an example in FIGS. 1 and 2.

During a phase of use, the wells 2 of the test card 1 are filled with afluid or test sample by means of known techniques for deposition invacuo. Conventionally, an end of a transfer tube 19 is inserted into theadmission port for the fluid 11 and attached into place. The other endof the transfer tube 19 is placed in a receptacle such as a test tubecontaining the fluid sample. The fluid is drawn off through the transfertube 19 as far as the admission manifold 12 which supplies the channels9 a, 9 b, 9 c ensuring transport of the fluid as far as the wells 2.

After this phase for introducing a fluid sample into the wells 2 of thetest card 1, the object of the invention is directed to applying a phasefor isolating at least one and preferably all the wells 2 of the testcard 1 in order to avoid cross-contamination between the wells.

The process or the method for achieving this isolation phase, as thisappears more particularly in FIGS. 3 to 5, consists of exerting a forceF on at least one portion of the covering area 17 ₁ of the adhesivemembrane 17, located overhanging or facing at least one channel, whichin the drawings is a distribution channel 9 a. Of course, applying aforce on at least one portion of the covering area 17 ₁ of the adhesivemembrane 17 located overhanging or facing a filling channel 9 c, may becontemplated.

The method according to the invention therefore consists of displacingat least one portion of the covering area 17 ₁ of the adhesive membrane17, in order to cause it to fit the shape of the wall 9 ₁ of the channelin order to allow adhesion of this portion of the covering area 17 ₁ ofthe adhesive membrane 17 onto the wall 9 ₁ of the channel (FIG. 4).Insofar that this portion of the covering area 17 ₁ of the adhesivemembrane 17 is brought into contact with the wall of the channel 9 a,the adhesive membrane 17 is capable of adhering or remaining adhesivelybonded by means of the adhesive 18, to the wall of the channel 9 a in anisolation area Zi (FIG. 5). It should be noted that the adhesivemembrane 17 is brought into contact with the wall of a channel, withoutdeformation of the support 3.

The application of a force F on the covering area 17 ₁ of the adhesivemembrane 17 in order to cause it to adhere to the wall of a channel maybe ensured by any suitable technical means. In the exemplary embodimentillustrated in FIGS. 3 to 5, the covering area 17 ₁ of the adhesivemembrane 17 is displaced by means of a pressing member 21 which is partof an obturation device 22. The pressing member 21 includes a supportingend 23 having a section mating the section of the channel.

In the example illustrated in FIGS. 3 to 5, the distribution channel 9 ahas a semi-circular cross-section of radius R. Thus the distributionchannel 9 a has a height or depth R and a width equal to 2R.

The pressing member 21 also has a supporting end 23 with a semi-circularsection of radius R′. Of course, the pressing member 21 is placedrelatively to the channels so as to obtain congruence between thesections of the channel and of the supporting end 23.

Advantageously, the supporting end 23 of the pressing member 21 has aradius R′ equal to the radius R of the channel, reduced by the thicknessof the adhesive membrane 17. The pressing member 21 ensures drawing ordeformation of the adhesive membrane 17 in its covering area 17 ₁ inorder to bring it into contact with the wall of the channel in order toallow the adhesive 18 to adhere to the wall of the channel.

It should be noted that the pressing member 21 has a supporting end 23with a general rounded shape in order to avoid piercing the adhesivemembrane 17. Thus, as this is apparent from FIG. 6, the pressing member21 has a rounded section in a plane parallel to the extension directionof the channel.

According to a preferred alternative embodiment, the pressing member 21exerts on the adhesive membrane 17, a pressure comprised between 0.3 and0.7 kg/cm² and preferably of the order of 0.6 kg/cm².

In the illustrated exemplary embodiments, each channel has asemi-circular cross-section. Of course, the channels may have sectionswith a different shape. Thus, provision may be made for making a channelwith a section comprised between a semi-circle of height R and of width2R on the one hand and a circular portion of width √5.R/3 and of heightequal to R/3 on the other hand. Typically, in the case of a channel witha semi-circular section, the radius R of the channel is comprisedbetween 50 μm and 2.5 mm and preferably between 150 μm and 500 μm.

In the example illustrated in FIGS. 3 to 5, the application of thesupporting force F on the covering area 17 ₁ of the adhesive membrane 17is obtained by ensuring a relative closing-in movement between thesupporting member 21 and the test card 1. After adhesion of the adhesivemembrane 17 on the wall of the channel, the pressing member 21 and thetest card 1 are moved away from each other.

In an exemplary embodiment illustrated in FIG. 6, the pressing member 21may be driven in order to move closer/move away relatively to the testcard 1 by means of an alternating linear displacement system of alltypes known per se. According to this alternative, the displacementsystem drives the sliding movement of the pressing member 21 along adirection T perpendicular to the face 4 or 5 of the test card 1.According to another exemplary embodiment, the test card 1 may bedisplaced so as to move closer/move away relatively to the pressingmember 21 which remains fixed.

According to an advantageous alternative embodiment, the methodaccording to the invention aims at exerting the force on the coveringarea 17 ₁ of the adhesive membrane 17, simultaneously with a relativedisplacement between the test card 1 and the pressing member 21 along adirection parallel to the extension direction of the channel in order toallow adhesion of the covering area 17 ₁ of the adhesive membrane 17onto at least one portion of the length of said channel, superior to thesupporting end of the pressing member 21.

As this emerges from FIG. 6, the pressing member 21 may have, inaddition to the translational movement T, perpendicular to the face 4, 5of the test card 1, a sliding movement C parallel to the face 4, 5 ofthe test card 1 and along the extension direction of the channel, i.e.according to an advantageous alternative embodiment, the length of adissolution channel 9 a.

FIG. 7 illustrates another alternative embodiment of a pressing member21 mounted so as to be mobile in rotation around an axis of rotation 25in order to roll on the bottom of the distribution channel 9 a and alonga portion of its direction taken along the extension direction C of thedistribution channel 9 a. According to this example, the pressing member21 appears as a roller, the circumference of which has a roundedcross-section mating the section of the channel as indicated earlier.

According to a feature of the invention, it should be noted that theapplication of a force F on the adhesive membrane 17 coming into contactwith the wall of the channel leads to displacement of the adhesivelocated in the application area of this force. It should be understoodthat the major portion of the adhesive 18 is displaced by the pressingmember 21, in an obturation area Zo.

Thus, the displacement of the supporting member 21 along the extensiondirection C of the channels, as illustrated in FIG. 7, concomitantlyleads to the displacement of the adhesive 18. Indeed, during thedisplacement of the pressing member 21 inside the channel, a portion ofthe adhesive is driven away or pushed by the pressing member 21 whichacts like a roller-pressing member. The adhesive 18 is thereforeestablished in at least one obturation area Zo adjacent to the isolationarea Zi. It should be noted that in this isolation area Zi, the adhesivemembrane 17 either adheres or not to the wall of the channel, what isimportant is that the adhesive driven away will obturate the channelupstream from the sample wells.

It should be noted that this roller-pressing effect may be obtained witha pressing member 21 exclusively displaced translationally Tperpendicularly to a face of the test card 1. In this case, the adhesive18 is driven on either side of the area of application of the pressingmember 21, in the distribution channel 9 a, or even in a filling channel9 c when the area of application of the force is located in this channelor at the intersection between a distribution channel 9 a and a fillingchannel 9 c.

The method according to the invention consists of selecting one orseveral locations of the covering area 17 ₁ of the adhesive membrane 17,so as to create in a channel, an isolation area Zi and subsequently anobturation area Zo for at least one well 2 and preferably for each well2, avoiding contamination between the whole of the wells of the card.These isolation areas Zi for the wells 2 may be made in any suitablelocations of the distribution channels 9 a and of the filling channels 9c in order to ensure isolation of the wells from each other. Theseisolation areas Zi extend over a more or less significant length ofthese channels.

According to a first alternative embodiment, provision may be made forproducing an isolation area Zi on each filling channel 9 c of a well 2.

According to a second embodiment, provision may be made for producingisolation areas Zi in the distribution channels 9 a, at the intersectionwith the filling channels 9 c and/or between two neighboring fillingchannels 9 c opening into the distribution channel 9 a.

According to a first exemplary embodiment, each isolation area Zi has apoint-like nature in the sense that the portion of the covering area 17₁ of the adhesive membrane 17 adhering to the wall of the channel has alimited surface area with respect to the length of the channel. FIG. 6in a schematic and enlarged way, illustrates the making of an isolationarea Zi with a point-like nature, by means of a pressing member 21 withlimited length relatively to the length of the channel. The displacementmovement of the pressing member 21 along the direction T gives thepossibility of obtaining an isolation area Zi in the channel, at rightangles to the pressing member. Such a movement of the pressing member 21is capable of causing concomitant displacement of the adhesive 18 whichmay obturate a filling channel 9 c which opens into the distributionchannel 9 a at right angles to the application of the supporting force.Of course, simultaneously producing several isolation areas Zi with asmany pressing members 21 or successively with one or several pressingmembers 21 displaced in different locations of the test card 1, may becontemplated.

According to a second exemplary embodiment, the isolation area Zi has anextended nature. For this purpose, either the pressing member 21 has asupporting end of a large dimension, or the pressing member 21 isdisplaced relatively to the test card 1 along the extension direction Cof the channel (FIG. 7).

According to a feature of the invention, the method according to theinvention consists of producing an isolation area Zi over the length ofthe distribution channel 9 a into which the filling channels 9 c open.Advantageously, this isolation area Zi is continuous over the wholelength into which open the filling channels 9 c. The result is that allthe wells 2 communicating with these filling channels 9 c are isolatedfrom each other.

According to an advantageous aspect of the invention, the methodaccording to the invention gives the possibility, by means of thedisplacement of the pressing member 21 inside the distribution channels9 a, of obtaining concomitant displacement of the adhesive 18 in thefilling channels 9 c, opening into the distribution channels 9 a. Thus,the test card 1 includes a continuous isolation area Zi on eachdistribution channel 9 a, over the whole of its length, includingintersections with the filling channels 9 c in order to ensure theirisolation. Further, each filling channel 9 c includes an obturation areaZo provided with the adhesive 18, which is contiguous or adjacent withthe obturation area Zo of the distribution channel 9 a. Such anarrangement ensures inter-well isolation 2 insofar that the adhesive 18will fill a section of the filling channels 9 c.

It emerges from the foregoing description that regardless of the mode ofapplication of the force on the adhesive membrane 17, in an isolationarea Zi, this force according to the invention leads to displacement ofthe major portion of the volume of the adhesive located in thisisolation area and on which the supporting member 21 acts.Advantageously, the force exerted on the adhesive membrane 17 is adaptedso as to ensure the displacement of a volume of adhesive 18, greaterthan the volume of the obturation area Zo of the channel 9 a, 9 c inorder to guarantee obturation of said channel with the displaced volumeof adhesive 18. For example, the displaced volume of adhesive 18 istwice the volume of the channel to be obturated in order to obtain ahermetic seal of the channel.

It emerges from the foregoing description that the method according tothe invention is simple to apply since it requires the application of aforce on the covering area 17 ₁ of the adhesive membrane 17 in order toallow its adhesion on the wall 9 ₁ of the channel and displacement ofthe adhesive 18 driven away following application of this force. Thesupport 3 does not undergo any deformation during the application ofthis force, giving the possibility of preserving the integrity of thesample wells. In the examples described above, application of this forceis ensured via a pressing member 21 with a section mating the section ofthe channel. Of course, the displacement of the covering area 17 ₁ ofthe adhesive membrane 17 may be ensured in a different way. For example,applying the supporting force on the covering area 17 ₁ of the adhesivemembrane 17 may be contemplated by means of an air jet.

According to an advantageous alternative, the obturation device 22 isapplied within the scope of a processing machine for test cards 1 as forexample described by U.S. Pat. No. 7,601,300; U.S. Pat. No. 5,798,085;U.S. Pat. No. 5,853,666 or U.S. Pat. No. 5,888,455.

Conventionally, a processing machine for test cards includes asuccession of processing stations, i.e. notably a loading station, astation for identifying the test cards, a station for sealing the testcard with respect to the outer environment, an incubation station and astation for reading test cards. Of course, such a machine includesconveying means allowing displacement of the test cards inside thestations and from one station to the other.

Advantageously, the phase for isolating the wells 2 by means of themethod according to the invention is achieved during a translationalmovement of the test cards 1, performed just after the filling with thesample to be tested and prior to the reading station. Thus, during thedisplacement of the test cards 1, the translational movement of the testcards is used in order to allow, during a portion of this translationalmovement, the application of the pressing member 21 on the covering area17 ₁ of the adhesive membrane 17 so as to allow its adhesion on the wallof the distribution channel 9 a. Thus, as the translational movement ofthe test cards 1 is parallel to the extension direction of thedistribution channel 9 a, the pressing member 21 may be rolled on thebottom of the distribution channel 9 a along all or part of its length.The result is that the obturation phase of the wells 2 may be achievedin hidden time since it may occur during a translational movement of thetest cards 1, performed by any conveying means with linear displacement,belonging to the processing machine. Thus, obturation of the wells 2 issimply obtained by fitting out the processing machine with an obturationdevice 22 according to the invention in proximity to conveying meansbelonging to the processing machine and ensuring translational movementto the test cards 1.

The invention is not limited to the described and illustrated examplessince diverse modifications may be made thereto without departing fromthe scope thereof.

The invention claimed is:
 1. A method for isolating at least one fluidsample well laid out in a test card for analysis, said test cardincluding a plate having at least one first main face from which is laidout at least one channel communicating with at least said well, thisfirst face being coated with a membrane provided with an adhesive andwhich will cover said channel with a covering area, the method forisolation including: a phase for introducing a fluid sample into atleast said well, a phase for isolating said well, along an isolationarea (Zi), consisting of exerting a force on at least one portion of thecovering area of the adhesive membrane for displacing it until causingit to fit the shape of the wall of a first channel so as to allowadhesion of said covering area of the adhesive membrane onto the wall ofthe first channel along the isolation area (Zi), comprising exerting aforce on the covering area of the adhesive membrane located overhangingthe first channel in order to ensure displacement of the adhesive fromthe isolation area (Zi) in an obturation area (Zo) for the sample well,contiguous to the isolation area (Zi), wherein the isolation areacomprises a portion of the first channel and the obturation areacomprises a portion of a second channel which opens into the firstchannel at an intersection between the first channel and the secondchannel, wherein axes of the first and second channels are not aligned.2. The method according to claim 1, comprising exerting the force on thecovering area of the adhesive membrane located overhanging the firstchannel for ensuring a displacement of a volume of adhesive greater thana volume of the obturation area of the second channel, in order toguarantee obturation of said second channel with the displaced volume ofadhesive.
 3. The method according to claim 1, comprising exerting theforce on the covering area of the adhesive membrane located overhangingat least one distribution channel, in order to ensure displacement ofthe adhesive in at least one obturation area (Zo) located in a fillingchannel communicating between a sample well and the distributionchannel.
 4. The method according to claim 1, comprising exerting theforce on the covering area of the adhesive membrane during the relativedisplacement between the test card and a pressing member along adirection parallel to the extension direction of at least onedistribution channel in order to ensure the displacement of the adhesivein a filling channel communicating with said distribution channel. 5.The method according to claim 1, comprising exerting a force on thecovering area of the adhesive membrane by means of a pressing memberhaving a supporting end with a section mating a section of the firstchannel.
 6. The method according to claim 1, comprising exerting a forceon the covering area of the adhesive membrane according to a pressurecomprised between 0.3 and 0.7 kg/cm².
 7. The method according to claim6, comprising displacing the test card along a direction correspondingto the translational movement of a system for displacing the test cardbelonging to a test card processing machine.
 8. A test card foranalyses, including a plate having at least one main face from which islaid out at least one channel communicating with at least one samplewell, the first face being coated with a membrane having an adhesivewhich covers said channel, with a covering area, at least one portion ofthe covering area of the adhesive membrane at least locally fits a shapeof a wall of the channel, in an isolation area (Zi), characterized inthat the test card includes at least one obturation area (Zo) for thesample well, adjacent to the isolation area (Zi) and filled with theadhesive of the adhesive membrane stemming from the isolation area (Zi),wherein the isolation area comprises a portion of a first channel andthe obturation area comprises a portion of a second channel which opensinto the first channel at an intersection between the first channel andthe second channel, wherein axes of the first and second channels arenot aligned.
 9. The test card according to claim 8, characterized inthat test card includes at least one obturation area (Zo) located in adistribution channel, at least at an intersection with at least onefilling channel for a sample well, the isolation area (Zi) adjacent tothe obturation area (Zo) being located in the filling channel.
 10. Thetest card according to claim 9, characterized in that the adhesivemembrane is coated with an adhesive having a thickness comprised between15 and 100 μm.
 11. The test card according to claim 10, characterized inthat the distribution or filling channel has a section comprised betweena semi-circle of height R and with a width equal to 2R on the one hand,and a circular portion of width √5.R/3 and with a height equal to R/3 onthe other hand.
 12. The method according to claim 6, wherein thepressure is on the order of 0.6 kg/cm².
 13. The method according toclaim 1, wherein the test card includes at least one fluid distributionchannel communicating with an admission port and connected to said atleast one well via at least one filling channel, and wherein the firstchannel is a distribution channel and the second channel is a fillingchannel.
 14. The method according to claim 1, wherein the test cardincludes at least one fluid distribution channel communicating with anadmission port and connected to said at least one well via at least onefilling channel, and wherein the first channel is a filling channel andthe second channel is a distribution channel.
 15. The test cardaccording to claim 8, wherein the test card includes at least one fluiddistribution channel communicating with an admission port and connectedto said at least one well via at least one filling channel, and whereinthe first channel is a distribution channel and the second channel is afilling channel.
 16. The test card according to claim 8, wherein thetest card includes at least one fluid distribution channel communicatingwith an admission port and connected to said at least one well via atleast one filling channel, and wherein the first channel is a fillingchannel and the second channel is a distribution channel.